ArrayList 的自定义方法 [英] Custom method for ArrayList

问题描述

您好，我想为 ArrayList 类创建一个自定义方法.

Hello I would like to make a custom method for ArrayList class.

假设我创建了一个新的 ArrayList.

So lets say I make a new ArrayList.

ArrayList<String> list = new ArrayList<String>

我想做一个可以在列表中调用的方法.像这样:

I would like to make a method I can call on list. Something like this:

list.myMethod();

我想用我的方法解决的是，您可以通过对象名称获取对象，而不是在 ArrayList 中获取索引.

What I want to solve with my method is so you can get an Object by Object name and not index inside the ArrayList.

所以基本上我想制作一个返回以下内容的方法:

So basically I want to make a method returning following:

list.get(list.indexOf(str));

总结一下:

    ArrayList<String> list= new ArrayList<>();
    String str = "asd";
    String str2 = "zxc";
    list.add(str2);
    list.add(str);
    System.out.println(list.get(0));
    System.out.println(list.get(list.indexOf(str)));

将打印:asd"asd".

Will print: "asd" "asd".

所以不要写:list.get(list.indexOf(Object))我希望能够编写 list.myMethod(Object) 并获得相同的结果.我希望你明白我的问题.我知道这可能是一个愚蠢的解决方案，我可以只使用地图.但这仅用于学习目的，我不会使用任何东西.

So instead of writing: list.get(list.indexOf(Object)) I would like to be a able to write list.myMethod(Object) and get the same result. I hope you understand my question. I know this is probably a dumb solution and I could just use a Map. But this is for learning purpose only and nothing I will use.

推荐答案

自定义方法>>

public class MyArrayList<E> extends ArrayList<E> {

    public E getLastItem(){
        return get(size()-1);
    }

}

如何使用>>

MyArrayList<String> list= new MyArrayList<>();
String str = "asd";
String str2 = "zxc";
list.add(str2);
list.add(str);
System.out.println(list.getLastItem());

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